Figure 6. Immunization decreased bacteria load in the lung tissue and blood, and recruited more neutrophils early after heterologous serotype virulent PAO-6 challenge.

Vaccine immunized mice, T lymphocytes transferred mice, CD4⁺ T lymphocytes depleted mice, IgG control mice and unimmunized mice were all challenged by 1 × 10⁷ CFUs PAO-6 cells. At 6 h (A), 18 h (B) after challenge the mice were anaesthetized, and the lung homogenate was collected and plated on agar plates (ANOVA, n = 7, *p < 0.05, **p < 0.01); At 6 h (C), 18 h (D) after challenge mice were anaesthetized, and the blood was collected and plated on agar plates (n = 4, ANOVA, *p < 0.05, **p < 0.01); (E) At 6h and 18h after PAO-6 challenge, lung tissue cells were recovered, firstly gated by CD45 and then stained by CD11b and Ly6G for neutrophil (CD45⁺ CD11b⁺ Ly6G⁺) identification. FACS data are presented with the means ± SD from all experiments for each group Results represent three independent experiments (n = 5, ANOVA, *p < 0.05, **p < 0.01).